Process for coating apparatuses and parts thereof

ABSTRACT

A process for coating surfaces in apparatuses or apparatus parts for plant construction, preferably for chemical plant construction, involves optionally first hydrophobicizing a polymer film having a microstructured and optionally additionally macrostructured surface and then fixing it on the apparatus or apparatus part to be coated, and also apparatuses and apparatus parts thus coated.

[0001] The present invention relates to a process for coating surfacesin apparatuses or apparatus parts for plant construction, preferably forchemical plant construction. The present invention further relates toapparatuses and apparatus parts coated with a polymer film having amicrostructured and optionally additionally macrostructured surface andbeing optionally first hydrophobicized and then fixed on the apparatusor apparatus part to be coated. By apparatuses and apparatus parts forplant construction are meant, for example, apparatus, tank and reactorwalls, tanks, discharge devices, valves, pumps, filters, compressors,centrifuges, columns, heat exchangers, dryers, centrifugal separators,scrubbers, comminution machines, internals, packing elements and mixingelements, used with preference in chemical plant. The present inventionfurther relates to apparatuses and apparatus parts coated by the processof the invention. Finally, the present invention relates to the use ofthe apparatuses or apparatus parts of the invention for chemical plantconstruction.

[0002] Settled and caked deposits in apparatuses and apparatus parts forplant construction represent a serious problem in industry, especiallyin the chemical industry. They particularly affect apparatus, tank andreactor walls, tank walls, discharge devices, valves, pumps, filters,compressors, centrifuges, columns, dryers, centrifugal separators,scrubbers, comminution machines, internals, packing elements and mixingelements. These deposits are also referred to as fouling.

[0003] These deposits may have a variety of damaging or hinderingeffects for the process and may make it necessary to shut down and cleancorresponding reactors or processing machines repeatedly.

[0004] Measurement devices encrusted with deposits may lead to incorrectand misleading results, through which operating errors may occur.

[0005] A further problem which arises as a result of the formation ofdeposits lies in the fact that, especially in deposits in polymerizationreactors, the molecular parameters such as molecular weight or degree ofcrosslinking differ significantly from the product specifications. Ifdeposits become detached in the course of ongoing operation, they maycontaminate the product (for example, gel specks in paints, inclusionsin suspension beads). In the case of reactor walls, packing elements ormixing elements, unwanted deposits may lead, furthermore, to an unwantedchange in the residence time profile of the apparatus or may impair theefficiency of the internals or mixing elements as such. Fairly coarsesections of deposits which break off may lead to blockage of dischargeand processing devices, while small parts may result in impairment ofthe product produced.

[0006] The deposits whose formation is to be prevented are coatingswhich may be caused, for example, by reactions with and on surfaces.Further reasons include adhesion to surfaces, which may be caused by vander Walls forces, polarization effects or electrostatic double layers.Other important effects are stagnation of movement at the surface andpossibly reactions in said stagnating layers. Finally, mention may bemade of the following: precipitates from solutions, evaporationresidues, cracking on locally hot surfaces, and microbiologicalactivity.

[0007] The causes are dependent on the respective combinations ofmaterial and may act alone or in combination. While the processesresulting in the unwanted coatings have been investigated quite well(for example A. P. Watkinson and D. I. Wilson, Experimental ThermalFluid Sci. 1997, 14, 361 and literature cited therein), the schemes forpreventing the above-described deposits are lacking in uniformity. Theprocesses known to date have technical disadvantages.

[0008] Mechanical solutions have the disadvantage that they may giverise to considerable additional costs. Additional reactor internals may,furthermore, significantly alter the flow profile of fluids in thereactors and as a result may necessitate an expensive redevelopment ofthe process. Chemical additives may lead to unwanted contamination ofthe product; some additives pollute the environment.

[0009] For these reasons, there is an increased impetus to the searchfor ways of directly reducing the fouling tendency by modification ofapparatuses and apparatus parts for chemical plant construction.

[0010] WO 00/40775, WO 00/40774 and WO 00/40773 describe processes forcoating surfaces, especially surfaces of reactors for high-pressurepolymerization of 1-olefins or surfaces of heat exchangers, byelectroless deposition of an NiP/polytetrafluoroethylene layer or aCuP/polytetrafluoroethylene layer by means of which the metal surfacesin question can be antiadhesively modified. When the surfaces coated bythe process described are used in apparatuses and apparatus parts forchemical plant construction, especially reactors for the high-pressurepolymerization of 1-olefins, however, it is observed that the surfacesare not sufficiently stable mechanically, so that following prolongeduse caked deposits of product are again observed. It is, however,impossible to recoat an NiP/polytetrafluoroethylene layer which has beenworn down only partially. Moreover, it is observed that anNiP/polytetrafluoroethylene layer, once deposited, is difficult toremove again if it is no longer desired in a reactor or apparatus part.Especially in reactors with rapid product change, in which occasionallyreactions are to be carried out at above 400° C., a coating withNiP/polytetrafluoroethylene has been found inappropriate. A finaldisadvantage is that, especially when coating reactors of high volume,it is necessary to use large amounts of dipping baths, leading toconsiderable solvent wastes.

[0011] WO 96/04123 discloses self-cleaning surfaces which may be coatedwith polytetrafluoroethylene and have particularly hydrophobicproperties. The structuring is brought about by incipient etching orembossing of the surface, by physical methods such as sandblasting orionic etching using, for example, oxygen. Subsequently, the surface iscoated with Teflon. The mechanical stability of coats hydrophobicized inthis way, however, is much too low for use in chemical apparatusconstruction, especially for polymerization reactors, where strong shearforces act.

[0012] Furthermore, structured surfaces having hydrophobic propertiesare known (EP-A 0 933 388) which are prepared by, for example,incipiently etching the surface in question, thus producing elevationsor grooves on the surface and subsequently covering them with a coat ofa hydrophobic polymer, polyvinylidene fluoride for example. These coatsmay further comprise fluorinated waxes, examples being Hostaflons®. Thesurfaces modified in this way are hydrophobic and oleophobic.Applications cited include wafer mounts in semiconductor production, andalso the preparation or coating of headlamps, windscreens or solar cellcovers. A disadvantage of the process, however, is that, followingpartial mechanical breakdown, the structuring is difficult to renew.

[0013] Finally, Tsujii et al. in Angew. Chem. 1997, 109, 1042 havepublished a process for rendering a microstructured metal surface (in,for example, aluminum which has been anodically oxidized) repellent tonumerous liquids by means of subsequent hydrophobicization. Again, thisprocess provides structuring which is difficult to renew. Moreover, thesurfaces prepared by the authors are still far removed from surfacesexhibiting ideal oil repulsion (p. 1044, middle).

[0014] It is an object of the present invention

[0015] to provide apparatuses and parts thereof with structured surfaceswhich have antiadhesive properties and which are easy not only to applybut also to remove again;

[0016] to provide a process for producing such apparatuses or partsthereof with structured surfaces.

[0017] We have found that this object is achieved by preparing a polymerfilm comprising a microstructured surface which may optionally have beenmacrostructured, first hydrophobicizing said film and then fixing it onthe apparatus or apparatus part to be coated. The surfaces treated inaccordance with the invention are hydrophobic and oleophobic and preventsettled and caked deposits.

[0018] The process of the invention comprises a number of steps. In thefirst, optional step, a surface to be protected against settled andcaked deposits is cleaned.

[0019] In the second step, a film is prepared from an appropriatematerial. Appropriate materials are polymers such as, for example,polycarbonates, especially Makrolon®, polystyrenes, styrene copolymerssuch as, for example, Terluran®, polyethylenes and ethylene copolymers,polypropylenes, polyethylene terephthalates (PET), polybutyleneterephthalates, polyvinyl chlorides and polyamides. This film issubsequently microstructured using known methods. The microstructuringmay be carried out, for example, by incipient etching or embossing ofthe surface, by physical methods such as blasting with an appropriatematerial, such as sand, or by incorporation of small, dust-sizedparticles. Moreover, chemical methods such as ionic etching with oxygen,for example, are suitable structuring processes. A preferred method isdescribed in EP-A 0 933 388, page 4, column 5, lines 39-50 and in R.Wechsung, Mikroelektronik 1995, 9, 34. The microstructuring of thesurface comprises elevations with an average height of from 50 nm to 10μm and a spacing of from 50 nm to 10 μm. Optionally, the film maycomprise a superstructure or macrostructure with elevations in anaverage height of from 10 μm to 1 mm and an average spacing of from 10μm to 1 mm. Polymer films having an additional macrostructure arenotable for the fact that they are able to withstand greater mechanicalstress, and they are much less sensitive to pressure, in particular,than those polymer films which merely have microstructuring.

[0020] Next, the surface is optionally hydrophobicized. A variety ofreagents may be used for hydrophobicizing.

[0021] Suitable hydrophobicizers are, generally, substances possessinglong linear or branched alkyl chains, long fluorinated alkyl chains ordimethylsiloxane chains. Particularly suitable terminal groups of thesechains are the methyl, trifluoromethyl and trimethylsilyl groups.

[0022] Examples of particularly suitable hydrophobicizers are:

[0023] polychlorotrifluoroethylene,

[0024] polytetrafluoroethylene,

[0025] poly-n-butyl methacrylate,

[0026] poly-tert-butyl methacrylate,

[0027] polyhexyl methacrylate,

[0028] poly-2-ethylhexyl methacrylate,

[0029] polybutyl acrylate,

[0030] poly-2-ethylhexyl acrylate,

[0031] poly dimethylsiloxane,

[0032] polyisobutene,

[0033] long-chain polyalkyl vinyl ethers having 8 to 36 carbon atoms inthe alkyl chain;

[0034] polyesters constructed from aliphatic or phenolic dialcoholshaving 2 to 18 carbon atoms on the one hand, e.g., 1,2-propanediol,1,3-propanediol, 1,4-butanediol, 1,6-hexanediol or bisphenol A, anddicarboxylic acids having 3 to 18 carbon atoms on the other hand, suchas adipic acid or decanedicarboxylic acid, for example. Suitablepolyesters are optionally terminated with long-chain monoalcohols having4 to 24 carbon atoms such as 2-ethylhexanol or octadecanol. Furthermore,the polyesters may be terminated with long-chain monocarboxylic acidshaving 4 to 24 carbon atoms, such as stearic acid, for example.

[0035] Polyesters constructed from terephthalic acid and aliphaticdialcohols having 2 to 18 carbon atoms, e.g., 1,2-propanediol,1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and dicarboxylic acidshaving 3 to 18 carbon atoms, such as adipic acid and decanedicarboxylicacid, for example. Suitable polyesters are optionally terminated withlong-chain monoalcohols having 4 to 24 carbon atoms, such as2-ethylhexanol or octadecanol.

[0036] Waxes such as, for example, polyethylene waxes, polypropylenewaxes, montanic acid waxes, montan ester waxes, amide waxes such asdistearoylethylenediamine, for example, Fischer-Tropsch waxes,polytetrafluoroethylene waxes, beeswax, carnauba wax, wool wax,candelilla wax, etc.

[0037] fatty acids having more than 8 carbon atoms,

[0038] fatty alcohols having more than 8 carbon atoms,

[0039] esters of fatty acids having more than 8 carbon atoms withmonofunctional alcohols,

[0040] esters of fatty acids having more than 8 carbon atoms withpolyfunctional alcohols such as, for example, glycerol, ethylene glycol,propylene glycol, sorbitol, glucose, sucrose and trimethylolpropane;

[0041] amides of fatty acids having more than 8 carbon atoms withmonofunctional amines,

[0042] amides of fatty acids having more than 8 carbon atoms withpolyfunctional amines such as, for example, ethylenediamine,diethylenetriamine, triethylenetetramine, polyethyleneimine andpolyvinylamine.

[0043] Copolymers containing structural elements of the formulae A to D:

[0044] where

[0045] n is an integer from 3 to 5 000

[0046] X¹-X⁶ are hydrogen,

[0047] C₁-C₃₆ alkyl, such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl,n-hexadecyl, n-octadecyl, n-eicosyl, n-C₃₀H₆₁ or n-C₃₆H₇₃;

[0048] C₁-C₃₆ alkoxy groups, preferably C₁-C₆ alkoxy groups such asmethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy, isohexoxy, n-octoxy,n-decoxy, O—n—C₂₀H₄₁, O—n—C₃₀H₆₁ or O—n—C₃₆H₃₇;

[0049] —O—C(═O)-C₁-C₃₆ alkyl, where C₁-C₃₆ alkyl is as defined above,

[0050] —(CH₂)_(a)—(CF₂)_(b)—CF₃, —O—(CH₂)_(a)—(CF₂)_(b)—CF₃ or—O—C(═O)—(CH₂)_(a)—(CF₂)_(b)—CF₃, where a is an integer from 0 to 6 andb is an integer from 1 to 16;

[0051] —(CH₂)_(a)—(O)_(c)—(Si(CH₃)₂O)_(d)—R where a is an integer from 0to 6, c is 0 or 1, d is an integer from 2 to 10 000 and R is H,Si(CH₃)₃, C₁-C₃₆ alkyl or O—C₁-C₃₆ alkyl and C₁-C₃₆ alkyl is as definedabove;

[0052] Further compounds suitable for hydrophobicizing are silanes ofthe formula R¹R²R³SiR⁴, where:

[0053] R¹ to R³ independently of one another are —H, —Cl, —OCH₃, —OC₂H₅,—OC₃H₇, —OC₄H₉;

[0054] R⁴ is

[0055] C₁-C₃₆ alkyl, such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl,n-hexadecyl, n-octadecyl, n-eicosyl, n-C₃₀H₆₁ or n-C₃₆H₇₃;

[0056] —(CH₂)_(a)—(CF₂)_(b)—CF₃ or —O—(CH₂)_(a)—(CF₂)_(b)—CF₃, where ais an integer from 0 to 6 and b is an integer from 1 to 16;

[0057] —OSi(CH₃)₃.

[0058] Further compounds suitable for hydrophobicizing are silicone oilswith or without Si—H groups and also silicone surfactants containing(H₃C)₃SiO—Si (CH₃)—OSi (CH₃)₃ groups, available commercially, forexample, from Wacker GmbH.

[0059] The hydrophobicizers are dissolved in an appropriate solvent andthen applied to the film, for example, by spraying, roll application ordipping of the film. Thereafter, the films are dried, optionally atelevated temperature (40-70° C.). Examples of appropriate solvents areacetone, ethanol, isopropanol, THF, petroleum spirit, toluene, andxylene.

[0060] Suitable concentrations of the hydrophobicizers are from 0.01 to5% by weight, preferably from 0.1 to 2% by weight, and with particularpreference from 0.3 to 1% by weight.

[0061] The film hydrophobicized and structured as described above isfixed to the surface to be protected against settled and caked deposits.Fixing may be done, for example, by adhesive bonding and laminatingprocesses. In principle, all common adhesives are suitable for adhesivebonding processes, such as solvent-based adhesives, water-basedadhesives, hot-melt adhesives, heat-curable adhesives and UV-curableadhesives. For instance, the surface to be protected may be sprayed witha spray adhesive, an example being Spray Mount® from Minnesota Miningand Manufacturing (3M), and then the film may be applied. Alternatively,the structured films may be provided with a self-adhesive layer and aneasily removable protective film. The protective film is then removedsimply by peeling and the film is adhered directly onto the surface tobe protected.

[0062] One particular embodiment of the present invention comprises aprocess for producing planar apparatus parts to be protected againstsettled and caked deposits, examples being planar metal sheets. Planarmetal sheets are advantageously laminated with the structured film, bypressing the film onto the sheet using a roller and so fixing it.

[0063] The apparatus parts coated in accordance with the process of theinvention may be used in numerous different kinds of apparatus for plantconstruction, chemical plant construction being preferred.

[0064] The apparatuses comprise liquid, gas/liquid, liquid/liquid,solid/liquid, gas/solid or gas reactors present, for example, in thefollowing embodiments: stirred-tank, jet loop and jet reactors, jetpumps, residence-time cells, static mixers, stirred columns, tubularreactors, cylindrical stirrers, bubble columns, jet and venturiscrubbers, fixed-bed reactors, reaction columns, evaporators,rotating-disk reactors, extraction columns, compounding and mixingreactors and extruders, mills, belt reactors or rotary tubes;

[0065] discharge devices comprise, for example, discharge ports,discharge funnels, discharge pipes, valves, discharge stopcocks orejection devices.

[0066] Valves comprise, for example, stopcocks, slide valves, burstingdisks, nonreturn valves or disks.

[0067] Pumps comprise, for example, centrifugal pumps, gear pumps, screwdisplacement pumps, eccentric screw pumps, annular rotating pistonpumps, reciprocating piston pumps, diaphragm pumps, screw trough pumpsor liquid jet pumps, and also reciprocating piston vacuum pumps,reciprocating piston membrane vacuum pumps, rotating piston vacuumpumps, rotating plunger vacuum pumps, liquid-ring vacuum pumps, rollerpiston vacuum pumps or fluid entrainment pumps, and also parts of saidpumps.

[0068] Filter apparatuses comprise, for example, fluid filters,fixed-bed filters, gas filters, sieves or separators.

[0069] Compressors comprise, for example, piston compressors, pistondiaphragm compressors, positive displacement rotary compressors, rotarypiston compressors, rotary multivane compressors, liquid-ringcompressors, rotary compressors, Roots compressors, screw compressors,jet compressors or turbo compressors.

[0070] Centrifuges comprise, for example, screen-type centrifuges orsolid-wall centrifuges, preference being given to disk centrifuges,solid-wall screw centrifuges (decanters), screen conveyor centrifugesand reciprocating pressure centrifuges.

[0071] Centrifugal separators comprise, for example, cyclones,multicyclones, centrifugal drop separators or rotary flow dustcollectors.

[0072] Scrubbers comprise scrubbing towers, jet scrubbers, cyclonescrubbers, rotary scrubbers or venturi scrubbers.

[0073] Columns comprise containers with exchange trays, preference beinggiven to bubble-cap, valve or sieve trays. In addition, the columns maybe filled with different packing elements, such as saddles, Raschigrings or beads, which may likewise be protected against contaminationusing polymer films in accordance with the invention.

[0074] Internals in reactors and containers comprise, for example,thermocouple sleeves, flow disruptors, foam breakers, packing elements,spacers, centering devices, flange connections, static mixers,analytical instruments such as pH or IR probes, conductivity measuringinstruments, level measuring instruments or foam probes.

[0075] Extruder elements comprise, for example, screw shafts and screwelements, extruder valves, plastification screws or injection nozzles.

[0076] The apparatus, container and reactor walls may comprise a varietyof materials, preference being given to metallic materials. Particularlypreferred materials are steels.

[0077] The abovementioned apparatuses are used preferably in chemicalplants but also in the food industry. Examples that may be mentionedinclude milk processing in dairies and the brewing of beer.

[0078] The surfaces in the abovementioned apparatuses or apparatusparts, when said surfaces have been treated by films adhered to them orapplied by lamination, are extremely difficult for liquids to wet,irrespective of whether the liquids are hydrophobic, oleophobic, ordispersions of hydrophobic and oleophobic liquids in the presence of oneor more emulsifiers. Neither hydrophobic nor oleophobic liquids leaveresidues on the surfaces treated in accordance with the invention.

[0079] The present invention additionally provides apparatuses orapparatus parts for chemical plant construction, comprising one or moredifficult-to-wet surfaces of the invention. No caked or settled depositsare observed on these walls, even in the course of prolonged use, andirrespective of whether the process in the reactor is carried out in anaqueous medium, in lipophilic solvents, or in emulsions usingemulsifiers. The apparatuses and apparatus parts coated in accordancewith the invention have excellent self-cleaning properties, asdescribed, for example, in R. Fürstner et al., Chem. Ing. Tech. 2000,72, 972. The mechanical stability of the surfaces treated in accordancewith the invention is good, and their service life is long. Finally, ithas been found that, even after prolonged use, the polymer films fixedin accordance with the invention, applied for example by adhesion orlamination, can be removed easily when required. This is the case inparticular when the polymer film has been fixed only to certainimportant points on the apparatus wall.

WORKING EXAMPLES Example 1

[0080] A negative mold was produced by UV lithography of aphotosensitive polymer (Ozatec NL 133 from Morton Electronic MaterialsGmbH) and subsequent electroforming with nickel. Using this negativemold, a polycarbonate film was cast. This film had a microstructure withelevations about 2 μm wide (measured at half-height) and 4 μm high in aspacing of 6 μm. The resulting film was hydrophobicized using DynasylanF (Degussa-Hüls AG), by dissolving the Dynasylan F at a concentration of0.1 percent by weight in isopropanol and spraying the solution onto thefilm with the aid of an air brush. A stainless steel plate was thensprayed with an aqueous solution of the adhesive Acronal V 210 (BASFAG). After the layer of adhesive had dried, the film was laminated ontothe adhesive-coated side of the stainless steel plate using a rubberroller. The film-coated stainless steel plate was mounted on a planartable with an angle of inclination of 20°. Then the following liquidswere applied dropwise using a pipette:

[0081] water with a drop mass of 46 mg

[0082] coffee with a drop mass of 54 mg

[0083] liquid honey available commercially from Langnese, with a dropmass of 80 mg

[0084] aqueous hydrochloric acid (32% by weight) with a drop mass of 44mg

[0085] aqueous sodium hydroxide solution (5% by weight) with a drop massof 52 mg

[0086] aqueous solution of a vinylpyrrolidone-vinylimidazole copolymer(30% by weight) with a drop mass of 40 mg

[0087] aqueous polymer dispersion Acronal® 290 D (BASF AG) with a dropmass of 58 mg

[0088] aqueous polymer dispersion Styronal® D 808 (BASF AG) with a dropmass of 54 mg

[0089] aqueous polymer dispersion Acronal® V210 (BASF AG) with a dropmass of 43 mg

[0090] None of the liquids caused wetting of the coated stainless steelplate. In all of the experiments, the drops ran in the form of beadsfrom the coated stainless steel plate without leaving any residues.

Comparative Example 1

[0091] In a comparative experiment, a smooth (unstructured) andunhydrophobicized polycarbonate film was laminated onto a stainlesssteel plate. Under the same conditions (same drop mass, 20° inclinationangle) the same test liquids as in Example 1 were applied dropwise. Inall of the experiments the surface was wetted, and all liquids, with theexception of water, left residues on the coated stainless steel plate.

Example 2

[0092] A structured but not additionally hydrophobicized polypropylenefilm (Huhtamaki Van Leer Packaging (Deutschland) GmbH & Co. KG, 4P FolieForchheim) was laminated onto a stainless steel plate as described inExample 1. The film-coated stainless steel plate was mounted on a planartable with an angle of inclination of 200. Then the following liquidswere applied dropwise using a pipette:

[0093] water with a drop mass of 46 mg

[0094] coffee with a drop mass of 54 mg

[0095] honey available commercially from Langnese, with a drop mass of80 mg

[0096] aqueous hydrochloric acid (32% by weight) with a drop mass of 44mg

[0097] aqueous sodium hydroxide solution (5% by weight) with a drop massof 52 mg

[0098] aqueous solution of a vinylpyrrolidone-vinylimidazole copolymer(30% by weight) with a drop mass of 40 mg

[0099] aqueous polymer dispersion Acronal® 290 D (BASF AG) with a dropmass of 58 mg

[0100] aqueous polymer dispersion Styronal® D 808 (BASF AG) with a dropmass of 54 mg

[0101] aqueous polymer dispersion Acronal® V210 (BASF AG) with a dropmass of 43 mg

[0102] None of the liquids caused wetting of the coated stainless steelplate. In all of the experiments, the drops ran in the form of beadsfrom the coated stainless steel plate without leaving any residues.

Comparative Example 2

[0103] In a comparative experiment, a smooth (unstructured) andunhydrophobicized polypropylene film was laminated onto a stainlesssteel plate. Under the same conditions (same drop mass, 20° inclinationangle) the same test liquids as in Example 2 were applied dropwise. Inall of the experiments the surface was wetted, and all liquids, with theexception of water, left residues on the coated stainless steel plate.

Example 3

[0104] The microstructured polycarbonate film from Example 1 waslaminated onto a stainless steel plate. The film-coated stainless steelplate was mounted on a planar table with an angle of inclination of 20°.Subsequently 100 mg/m² of fine carbon black (Printex V from Degussa-HülsAG, average diameter of the primary particles: 25 nm) were spread overthe plate laminated with the microstructured film. The plate was thenbriefly rinsed with water. Within a few seconds, carbon black was nolonger visually detectable on the surface.

Comparative Example 3

[0105] The unstructured polycarbonate film from Comparative Example 1was laminated onto a stainless steel plate. The film-coated stainlesssteel plate was mounted on a planar table with an angle of inclinationof 200. Subsequently 100 mg/m² of fine carbon black (Printex V fromDegussa-Hüls AG, average diameter of the primary particles: 25 nm) werespread over the plate laminated with the film. The plate was thenbriefly rinsed with water. Even after 5 minutes, carbon black was stillvisually perceptible on the film.

We claim:
 1. A process for coating surfaces in apparatuses or apparatusparts for plant construction, which comprises optionally firsthydrophobicizing a polymer film having a microstructured and optionallyadditionally macrostructured surface and then fixing it on the apparatusor apparatus part to be coated.
 2. A process for coating surfaces asclaimed in claim 1, wherein a polymer film is used which has amicrostructure comprising elevations with an average height of from 50nm to 10 μm and a spacing of from 50 nm to 10 μm and optionally amacrostructure with elevations in an average height of from 10 μm to 1mm and an average spacing of from 10 μm to 1 mm.
 3. A process forcoating surfaces as claimed in claim 1, wherein the structured polymerfilm is adhered to the apparatus or apparatus part to be coated.
 4. Aprocess for coating surfaces as claimed in claim 2, wherein thestructured polymer film is adhered to the apparatus or apparatus part tobe coated.
 5. A process for coating surfaces as claimed in claim 1,wherein the structured polymer film is laminated to the apparatus orapparatus part to be coated.
 6. A process for coating surfaces asclaimed in claim 2, wherein the structured polymer film is laminated tothe apparatus or apparatus part to be coated.
 7. An apparatus orapparatus part for plant construction having an optionallyhydrophobicized polymer film with microstructured and optionallyadditionally macrostructured surface fixed to its surfaces to beprotected against contamination.
 8. An apparatus or apparatus part asclaimed in claim 7, wherein the polymer film comprises elevations withan average height of from 50 nm to 10 μm and a spacing of from 50 nm to10 μm and optionally a macrostructure with elevations in an averageheight of from 10 μm to 1 mm and an average spacing of from 10 μm to 1mm.
 9. Chemical plant construction comprising apparatus or apparatusparts as claimed in claim
 7. 10. Chemical plant construction comprisingapparatus or apparatus parts as claimed in claim 8.